A dead language helps forge identity and esprit de corps, like boot camp for Marines.

It may not be surprising to learn that a charter school named Boys’ Latin still offers courses in this dead language. But it is surprising to learn that this is an all-black school in an iffy part of West Philadelphia, and Latin isn’t merely an option here. It’s a requirement.

Turns out, too, that the young men of Boys’ Latin have become pretty good at distinguishing their ad hominem from...